Here are some good websites I've found with interesting (and free of course) patterns, or some good info/guides dedicated to plastic canvas. Enjoy.
Some Extra Help and Guides
Freebie Patterns
T's Place Patterns
Plastic Canvas Crafts
Oscette's Plastic Canvas Page
June Bug's Patterns
Uniek's
Bev's Plastic Canvas World
Mountain Harmony Creations
Plastic Canvas Patterns for YOU
FreePatterns.com
Kreinik
TGAW Plastic Canvas Patterns
Craft Designs For You
All Crafts
Family crafts
